An example of an instruments of this type includes bipolar gripping forceps to grip and coagulate tissue. However, such instruments also may be other devices having different functions such as scissors.
In general, bipolar instruments comprise two arms pivotable about a support shaft and each is electrically conductively connected to a different terminal of a high frequency (hf) generator. The arms are made to pivot by a push/pull element displaceably mounted in the stem. The distal end of the push/pull element is connected to the arms by a suitable mechanism which converts axial displacement of the element into a pivoting motion of the arms. Said mechanism illustratively may be a knuckle joint or the like.
An instrument of this general type has been disclosed in German Gebrauchsmuster 296 04 191 which describes a coagulating gripping forceps wherein power is applied to one arm through the shank and to the other arm through the electrically conducting push/pull element. This known design is comparatively elaborate and requires careful insulation, especially in the area of the coupling between the arms and the distal end of the push/pull element also acts as an electric conductor.